You know the feeling — you stay up until the early hours working in front of your laptop, or you scroll through your Instagram feed on your phone before turning off the light, and then… you just can’t fall asleep. You know you’re tired — you were yawning just a minute ago. So what’s going on? Blame it on the blue light emanating from your electronic devices like your computer, tablet, and phone.

What is blue light?

Blue light is everywhere. Just step outside and you’ll get a good dose of it from the sun. Blue light also comes from light emitting diodes (LEDs), used in energy-efficient bulbs and to illuminate TV, computer, tablet, and smartphone screens. Blue light has a short wavelength, so it produces more energy than lights with longer wavelengths, like red light, do.

Blue light can be a good thing. Exposure during the day wakes you up and makes you more alert, and can even improve your mood. Blue-light emitting goggles and panels are used to treat a number of issues such as seasonal affective disorder (SAD), jetlag, and premenstrual syndrome.[1]

Blue light doesn’t just enter the body through the eyes — your skin absorbs it too. Hospitals use blue light to treat babies with jaundice — it helps get rid of the yellow pigment bilirubin in the blood.

Blue light and sleep

The problem is, newer artificial lights like LEDS and compact fluorescent light (CFL) bulbs don’t contain most of the infrafred, violet, and red light that’s found in sunlight, and instead increase the intensity of the blue light to a level that we aren’t evolved to handle. This is known as “junk light.”

You’re bombarded with junk light throughout the day and for much of the night — when you’re on your phone, working at your computer, or watching TV — and all this blue light exposure is ruining your sleep.[2][3] Blue light messes with your circadian rhythm by suppressing melatonin — the hormone that tells your brain when it’s time to sleep. Blue light tricks your body into thinking it’s daytime.

Normally, the pineal gland — a pea-sized gland in the brain — releases melatonin a couple of hours before you typically go to bed. But blue light can mess with this process, which in turn makes you less sleepy. Blue light does this by stimulating a type of light sensor — called intrinsically photosensitive retinal ganglion cells (ipRGCs) — in the retina of the eye. These sensors send light information to the circadian clock, telling it when it’s time for the body to sleep and to wake up.[4]

A 2014 study found that people who read from a light-emitting device before bed took longer to fall asleep, slept less deeply, and were more alert than people who read a printed book.[5]

The health risks of blue light

Too much blue light at night has been linked to serious health issues. Your mitochondria — the power generators in your cells — have to produce loads more energy to process blue light. When the mitochondria in your eyes are overtaxed, the rest of your mitochondria can get stressed too. This causes inflammation throughout the body, increasing your risk for serious and chronic disease. These include:

Cancer: A recent study found a direct link between blue light exposure and an increased risk of breast cancer and prostate cancer. People exposed to high levels of outdoor blue light, like street lights, at night had a higher risk of developing breast cancer and prostate cancer, compared with those who were less exposed.[6]Other studies have found that a disrupted circadian clock increases your risk for cancer.[7]

Diabetes and weight gain: A 2016 study found that adults who were exposed to blue light while eating in the evening had higher glucose levels, slower metabolisms, and more insulin resistance compared to adults who ate in dim light.[8]

Vision loss: Blue light can lead to macular degeneration — damage to the retina that often leads to vision loss.[10] More than 11 million people over the age of 60, including my father, have some form of macular degeneration, so it’s an issue that hits close to home.[11]

How to protect yourself from blue light

I’m a night owl, which means I’m genetically wired to stay up late. I wrote through the night to finish my bestselling book “Headstrong,” but my circadian rhythm remained intact because I took precautions: I used a light filter app to change my computer screen from blue to red; I wore my TrueDark blue-light blocking glasses; and I used a red light bulb. So even though I was awake, my brain got a proper signal from the environment that it was night.

Here’s how you can shield yourself from blue light overexposure:

Unplug unnecessary electrical devices in your bedroom: Go through your room and unplug or tape over LEDs to black out your sleep area. I carry electrical tape with me when I stay in hotels so I can tape over the omnipresent blue LEDs that mess with my sleep.

Invest in blackout curtains. If you try just one sleep hack, make it this one — it’s a serious game-changer. A dark room equals better sleep. But watch out for the light that seeps in all around the edges of the curtains. Buy some velcro and tape down the sides, and put a valance on top. Or you can use foil over your windows. Not exactly stylish, but you’ll be winning at sleep. That’s a fair trade-off in my book.

Switch to amber or red bulbs: Throw outthose compact fluorescent lights (the curly bulbs). They give off high amounts of blue light and cause eye strain.

Wear blue light blocking glasses: Usually orange- or red-tinted, these glasses aren’t the sexiest look, but they block harmful wavelengths.

Switch to “Night Shift” mode on your iPhone, iPad, and iPod Touch: While it’s best you put all devices down before bed, that’s not always possible in this exciting, technology-driven world. Apple has a cool, relatively unknown hack to adjust the colors of your screen to warmer tones. It’s called Night Shift, and it takes just a minute to set up. Swipe up from the bottom edge of any screen and press firmly on the brightness icon. Then tap the Night Shift icon to turn it on or off. Once you’ve done that, go to Settings>Display & Brightness > Night Shift. Here you can schedule when you want Night Shift to turn on and off (from sunset to sunrise, for example). You can also adjust the color to be warmer or cooler.

Install light filter apps: If you don’t have an Apple device, you can use apps like f.lux or Iris (that’s my pick), which adjust your display’s color temperature depending on the time of day.

Shut down all electronic devices at least two hours before bed: This isn’t always realistic, but when you can, do it.

Take carotenoid supplements: Your eyes need macular carotenoids — pigments that act as antioxidants — to protect them from junk light. Carotenoids lutein, zeaxanthin, and astaxanthin work together to protect the retina and reduce oxidative stress caused by blue light. That’s why I choose to supplement withEye Armor, which is full of vision-protecting carotenoids and antioxidants.

Increase your exposure to high-quality light sources:Make sure you spend some time outdoors in the sun to balance your exposure to artificial junk light. Invest in some simple LED red bulbs, or switch to halogen lamps if possible. Another way to increase your healthy light exposure is to sit in an infrared sauna. These are simple ways to boost your energy and mental performance.

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Dave Asprey is founder & CEO of Bulletproof, and creator of the widely-popular Bulletproof Coffee. He is a two-time New York Times bestselling author, host of the Webby award-winning podcast Bulletproof Radio, and has been featured on the Today show, Fox News, Nightline, Dr. Oz, and many more.

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